MySQL Add, modify, delete table columns and constraints, such as the definition of table _mysql

ALTER table: Add, modify, delete table columns, constraints, and other table definitions.

View column: Desc table name;
Modify table name: ALTER TABLE T_book Rename to BBB;
Add column: ALTER TABLE name add column name varchar (30);
Delete column: ALTER TABLE name drop column column name;
Modify Column name Mysql:alter table BBB change nnnnn hh int;
Modify Column name Sqlserver:exec sp_rename ' t_student.name ', ' nn ', ' column ';
Modify Column name oracle:lter table BBB Rename column nnnnn to HH int;
Modify Column properties: ALTER TABLE T_book modify name varchar (22);

Sp_rename:sqlserver built-in stored procedures, with the definition of modifying the table.

MySQL view constraints, add constraints, delete constraints Add columns, modify columns, delete columns

View table field information: DESC table name;
View all information about the table: Show create table name;
Add PRIMARY KEY constraint: ALTER TABLE name add constraint primary key (like: Pk_ table name) primary key table name (primary key field);
Add FOREIGN KEY constraint: ALTER TABLE references primary table (primary key field) from table Add Constraint foreign key (shape: Fk_ from Table _ Main Table) foreign key from table (foreign key field);
Delete PRIMARY KEY constraint: ALTER TABLE name drop PRIMARY key;
Delete FOREIGN KEY constraint: ALTER TABLE name drop FOREIGN key foreign (case-sensitive);

Modify table name: ALTER TABLE T_book Rename to BBB;
Add column: ALTER TABLE name add column name varchar (30);
Delete column: ALTER TABLE name drop column column name;
Modify Column name Mysql:alter table BBB change nnnnn hh int;
Modify Column name Sqlserver:exec sp_rename ' t_student.name ', ' nn ', ' column ';
Modify Column name oracle:alter table BBB Rename column nnnnn to HH int;
Modify Column properties: ALTER TABLE T_book modify name varchar (22);

Sp_rename:sqlserver built-in stored procedures, with the definition of modifying the table.

Delete primary Key first
ALTER TABLE table_test drop PRIMARY key;

And then add the primary key
ALTER TABLE Table_test add primary key (ID);
ALTER TABLE test rename test1; --Modifying the table name

ALTER TABLE test Add column name varchar (a) not null; --Adding table columns

ALTER TABLE wd_express drop column ID; --Delete Table columns
ALTER TABLE wd_express drop column tbid; --Delete Table columns
ALTER TABLE wd_express change column express_id ID int; --Modifying table column names

ALTER TABLE wd_express add PRIMARY key (ID);

ALTER TABLE test Modify address char (10)--Modify table column type
|| ALTER TABLE test change address char (40)

ALTER TABLE test Change column address Address1 varchar (30)--Modify table column name